By Alan Harman
Changing environmental conditions around the globe – including the disappearance of pollinators – caused by human activity could threaten the health of millions of people by altering the amount and quality of key crops, two new studies from Harvard University warn.
The first finds that decreasing numbers of food pollinators such as bees, falling in part due to pesticide use and destruction of habitats, could lead to declines in nutrient-rich crops that have been linked with staving off disease.
The second says increasing levels of atmospheric carbon dioxide (CO2) could lead to lower levels of zinc in food and thus to greatly expanded zinc deficiency.
The studies are published in The Lancet and Lancet Global Health in conjunction with a Rockefeller Foundation-Lancet Commission on Planetary Health report that broadly assesses the scale of the threats to health, development, and civilization posed by the deluge of environmental changes brought on by human activity.
“This is the first time that the global health community has come out in a concerted way to report that we are in real danger of undermining the core ecological systems that support human health,” says Samuel Myers, senior research scientist in the Harvard Chan School’s Department of Environmental Health.
“All of human civilization has taken place during a very stable set of biophysical conditions, but we are now changing those conditions at a rate that’s never been seen before,” Myers says.
“Whether we’re talking about land use, deforestation, degradation of global fisheries, disruption of the climate system, biodiversity loss, appropriation of fresh water, changes to aquatic systems–all of the changes are profound and they’re accelerating, and they represent a significant challenge to global health.”
In the study of pollinators, Myers and his colleagues looked at people’s dietary intake data for 224 types of food in 156 countries to quantify total per capita intake of vitamin A, folate, fruits, vegetables, and nuts and seeds under various pollinator decline scenarios. They then estimated the potential health impacts of declines in pollinators – mostly bees and other insects.
Pollinators play a key role in roughly 35% of global food production and are directly responsible for up to 40% of the world’s supply of micronutrients such as vitamin A and folate, which are vital for children and pregnant women.
The researchers found that the complete loss of animal pollinators globally would push an additional 71 million people into vitamin A deficiency and 173 million more into folate deficiency, and would lead to about 1.42 million additional deaths per year from non-communicable diseases (NCDs) and malnutrition-related diseases–a 2.7% increase in total yearly deaths.
A 50% loss of pollination would result in roughly half that impact, the researchers found.
Most of this burden of disease would result from reduced consumption of foods that protect against NCDs such as heart disease, stroke, and certain cancers and, unlike the populations frequently impacted by environmental degradation, many of the most vulnerable populations reside in relatively developed countries.
Researchers found that those most vulnerable would be in eastern Europe and in central, eastern, and Southeast Asia, where risks of NCDs are high and intake of fruits, vegetables, nuts, and seeds is highly dependent on pollinators.
The study also found that most of the estimated pollinator-related disease burden had to do with locally produced crops and not imported ones.
“This means that most countries can benefit greatly by managing their own pollinator populations, protecting both their public health as well as crop yields,” says lead author Matthew Smith, research fellow in Harvard’s Department of Environmental Health.
For the study on zinc, the authors modeled how much zinc would be available to people through diet in 188 countries, under both current and elevated levels of CO2. They noted that zinc is a key nutrient for maternal and child health–without enough, there is increased risk of premature delivery, reduced growth and weight gain in young children, and decreased immune function. Roughly 17% of the global population was estimated to be at risk of zinc deficiency in 2011, according to recent studies.
Citing previous research that found that elevated concentrations of atmospheric CO2 lowers the content of zinc and other nutrients in important food crops such as wheat, rice, barley, and soy, the authors estimated that CO2 emissions caused by human activity could place between 132 million and 180 million people at new risk of zinc deficiency by around 2050.
Those most likely to be affected live in Africa and South Asia, and nearly 48 million people in India alone – populations already burdened with the world’s highest levels of zinc deficiency, and reliant on crops for most of their dietary zinc.
The authors suggest possible interventions for those at highest risk for zinc deficiency, such as zinc supplementation, fortification of staple foods with additional zinc, the application of zinc-containing fertilizers to crops, or the development of bio-fortified strains of crops such as rice and wheat.
Richard Horton, editor-in-chief of The Lancet says the reports aims to put the health of human civilizations, and their special relationship with the larger biosphere, at the center of concerns for future planetary sustainability.
“Our civilization may seem strong and resilient, but history tells us that our societies are fragile and vulnerable,” he says/
Rockefeller Foundation president Judith Rodin says the reports give a dire warning.
“Human action is undermining the resilience of the earth’s natural systems, and in so doing we are compromising our own resilience, along with our health and, frankly, our future,” she says.
“We are in a symbiotic relationship with our planet, and we must start to value that in very real ways.”
